Systems for handling and dispensing fluids, either liquid or gaseous, are in wide use for a variety of purposes. Among such systems are those used to handle and dispense liquids which are, to a greater or lesser degree, hazardous to life forms, e.g., humans, plants or animals. Such liquids may be caustic, corrosive, flammable or explosive and in addition to being hazardous to life forms, are capable of damaging the atmospheric or soil environment.
An exemplary type of such system is used to dispense hydrocarbon liquids such as oil, kerosene, diesel fuel, jet fuel or gasoline. U.S. Pat. No. 3,910,102 (McLean) depicts such a system used to dispense gasoline.
Gasoline dispensing systems represent a particularly important example of systems of the foregoing types. This is so since such dispensing systems are in very wide use (every automobile filling station has at least one) and because gasoline is a volatile organic compound (VOC) which evaporates quickly into the atmosphere.
Further, gasoline rapidly soaks into the earth and can pollute underground water aquifers, an important source of drinking water. And the expense related to cleaning up an inadvertent gasoline spill can be enormous--it is not an exaggeration to say that a ground-soaking spill involving $100 worth of gasoline may require an expenditure in the range of $50,000-100,000 to clean up.
A corollary fact is that gasoline dispensing systems (and perhaps other types of systems handling hazardous liquids) are periodically required to be tested, at least under current federal regulations. Such testing involves, among other things, diagnostic tests (conducted using test ports and/or temporarily-installed fittings) intended to determine whether or not the system may be leaking liquid into the environment. Japan patent document 58-27041 and U.S. Pat. No. 3,958,449 (Drescher et al.) both relate to methods for detecting a pipe line leak.
Current gasoline dispensing systems are equipped with a leak detector which is usually mounted very near the underground storage tank or near the pump used to draw gasoline from such tank. To perform system integrity tests, the leak detector is removed and a special test attachment temporarily installed in its place.
Current systems also have an impact valve located directly beneath the gasoline dispenser or "pump" as it is referred to by most motorists. The impact valve automatically closes if the liquid-carrying pipe is sheared off as when a vehicle strikes the pump at sufficient speed. Such impact valve has a test port used (after removing the port plug) for making system integrity tests.
Such current systems are characterized by certain disadvantages. Other than the aforedescribed test points (at the leak detector location and at the impact valve), the only way to obtain one or more additional test points is to open the line carrying gasoline (usually by removing a pipe union) and install the necessary hardware for each desired point. There is no provision for bleeding line pressure down to ambient so that such line can be opened without resulting in gasoline squirting geyser-like when the line is opened. A spill is all but inevitable when opening such a line in that way. And there is no satisfactory provision for "dividing" the length of the liquid-carrying line into several discrete lengths which can be separately tested to determine whether that particular length is leaking.
Another disadvantage relates to the actual testing activity. When conducting a test, test port plugs are removed and a test device, e.g., a gauge, a source of pressurized inert gas (nitrogen or the like), is attached to the port. In so doing, a liquid spill is very likely to occur. For example, if the port is somewhat below liquid level in, say, a pump/turbine housing, the liquid will drain out the port by force of gravity until the level of such liquid reaches that of the port.
And the system may have a pressurized vapor or air "bubble" trapped somewhere in it. Opening a port permits the pressurized "bubble" to expand, forcing liquid out the port. While the amount of liquid so spilled is often relatively modest, perhaps a gallon or less, spills of several gallons are not unusual.
Yet another disadvantage of current systems is that such test ports are in places which are difficult to reach or work in. The space below the dispenser is very crowded. The resulting frustration of the testing technician has caused more than one unscrupulous technician to fail to conduct a proper test and yet give a favorable report on the system's integrity.
A test apparatus which addresses such disadvantages would be an important advance in the art.